Blood Flashcards
(44 cards)
Explain the composition of Blood
Blood
It is composed of liquid plasma and formed elements
Formed elements include:
- Erythrocytes, or red blood cells (RBCs)
- Leukocytes, or white blood cells (WBCs)
- Trombocytes, or platelets
Where does Hematopoesis takes place?
Hematopoesis
Blood cell formation, Hematopoesis, takes place in the red bone marrow
How much percentage of body weight does Blood account for?
Blood accounts for approximately 8% of body weight
What is the average volume of blood?
Average volume: 5–6 L for males, and 4–5 L for females
Give example of solutes in Blood Plasma.
Blood Plasma contains over 100 solutes, including;
- Proteins – albumin, globulins, clotting proteins, and others
- Lactic acid, urea, creatinine
- Organic nutrients – glucose, carbohydrates, amino acids
- Electrolytes – sodium, potassium, calcium, chloride, bicarbonate
- Respiratory gases – oxygen and carbon dioxide
Explain Erythrocytes.
Erythrocytes (RBCs)
- Biconcave discs, anucleate, essentially free of organelles
- Filled with hemoglobin (Hb), a protein that functions in gas transport
Describe Hemoglobin and the differenet phases during gas transportation
Structure of Hemoglobin
- Each Hb molecule can transport four molecules of oxygen bound to the heme groups
- Oxyhemoglobin – Hb bound to oxygen
- Oxygen loading takes place in the lungs
- Deoxyhemoglobin – Hb after oxygen diffuses into tissues (reduced Hb)
- Carbaminohemoglobin – Hb bound to carbon dioxide
- Carbon dioxide loading takes place in the tissues
What is the turnover of red blood cells (RBC)
Turnover of red blood cells (RBC)
- The life span of an erythrocyte is 100–120 days
What happens if you have too many or too few RBC:s?
Erythrocytes
The number of circulating erythrocytes remains constant and reflects a balance between RBC production and destruction:
- too few RBCs leads to tissue hypoxia (pale and/or cyanotic skin!)
- too many RBCs, polycythemia, causes undesirable blood viscosity (blushing skin!)
Explain Erythropoiesis
Production of Erythrocytes: Erythropoiesis
Developmental stages of erythroblasts.
Erythropoiesis requires:
- Iron
- Vitamin B12
- Folic acid
Explain Hormonal Control of Erythropoiesis
Hormonal Control of Erythropoiesis
Explain Erythrocyte Destruction and Heme Metabolism
Erythrocyte Destruction and Heme Metabolism
- Dying RBCs are engulfed by macrophages mainly in the spleen
- Heme and globin are separated and the iron is saved for reuse
- Heme is degraded to a yellow pigment, bilirubin, that is concentrated in the liver (icterus or jaundice in liver disease!)
- The liver secretes conjugated bilirubin into the intestines along with the bile
- The intestines metabolize bilirubin to a brownish pigment in feces
Explain symptoms and causes of Anemia
Anemia
- Signs and symptoms include fatigue, paleness, shortness of breath, and chills
- Various causes:
- Iron-deficiency (secondary to hemorrhage; inadequate intake; impaired absorption)
- Deficiency of vitamin B12 (inadequate intake; impaired absorption)
- Premature RBC destruction (genetic; autoimmune)
- Defective erythropoesis (leukemia and other myeloproliferative disorders)
Explain Sickle-Cell Anemia
Anemia: Abnormal Hemoglobin
- Sickle-cell anemia – results from a defective gene coding for an abnormal Hb called hemoglobin S (HbS)
- HbS has a single amino acid substitution in the beta chain; this defect causes RBCs to become sickle-shaped in low oxygen situations
Explain Leukocytes
White blood cells (WBCs), also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells. Leukocytes are found throughout the body, including the blood and lymphatic system.
How does the classification of Leukocytes look like?
White blood cells - Leukocytes
A. Granular leukocytes (contain conspicuous granules
that are visible under a light microscope after staining)
1. Neutrophils
2. Eosinophils
3. Basophils
B. Agranular leukocytes (no granules are visible under a
light microscope after staining)
1. T and B lymphocytes and natural killer cells
2. Monocytes
How does the distribution of Leukocytes look like?
Leukocytes
Describe Neutrophils
Neutrophils
- Neutrophils have two types of granules that:
- Take up both acidic and basic dyes
- Give the cytoplasm a lilac color
- Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins)
- Neutrophils are our body’s bacteria slayers
Describe Eosinophils
Eosinophils
- Eosinophils account for 1–4% of WBCs
- Have red-staining, bilobed nuclei connected via a broad band of nuclear material
- Have red to crimson (acidophilic) large, coarse, lysosome-like granules
- Lead the body’s counterattack against parasitic worms
- Lessen the severity of allergies by phagocytizing immune complexes
Describe Basophils
Basophils
- Account for 0.5% of WBCs and:
- Have U- or S-shaped nuclei with two or three conspicuous constrictions
- Are functionally similar to mast cells
- Have large, purplish-black (basophilic) granules that contain histamine
- Histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect)
Describe Lymphocytes
Lymphocytes
- Account for 25% or more of WBCs and:
- Have large, dark-purple, circular nuclei with a thin rim of blue cytoplasm
- Are found mostly enmeshed in lymphoid tissue (some circulate in the blood)
- There are two types of lymphocytes: T cells and B cells
- T cells function in the immune response
- B cells give rise to plasma cells, which produce antibodies
Describe Monocytes
Monocytes
- Monocytes account for 4–8% of leukocytes
- They are the largest leukocytes
- They have abundant pale-blue cytoplasms
- They have purple-staining, U- or kidney-shaped nuclei
- They leave the circulation, enter tissue, and differentiate into macrophages
Describe Macrophages
Macrophages
- Are highly mobile and actively phagocytic
- Activate lymphocytes to mount an immune response
Phagocytes are cells that protect the body by ingesting (phagocytosing) harmful foreign particles, bacteria, and dead or dying cells.
Explain Platelets
Platelets
Pluripotent stem cells also differentiate into cells that produce
platelets (see Figure 14.2a). Some myeloid stem cells
develop into cells called megakaryoblasts, which in turn transform into megakaryocytes, huge cells that splinter into
2000–3000 fragments in the red bone marrow and then enter
the bloodstream. Each fragment, enclosed by a piece of the
megakaryocyte cell membrane, is a platelet. Between 150,000
and 400,000 platelets are present in each L of blood.
Platelets are disc-shaped, have a diameter of 2–4 m, and exhibit
many vesicles but no nucleus. When blood vessels are
damaged, platelets help stop blood loss by forming a platelet
plug. Their vesicles also contain chemicals that promote
blood clotting (both processes are described shortly). After
their short life span of 5–9 days, platelets are removed by
macrophages in the spleen and liver.
